High pressure X-ray diffraction on UX2 compounds

High pressure X-ray diffraction was performed on several intermetallic uranium compounds UX$_2$ (X Co, Fe, Mn, Ir, Al). All the compounds have the same structure at atmospheric pressure (cubic MgCu2 type). For UMn$_2$, UFe$_2$, UCo$_2$ and UIr$_2$, this structure remains stable in the pressure range investigated. In the case of UAl$_2$, a transformation to a not yet identified new structural phase is observed around 10 GPa. The bulk moduli of all compounds have been determined using the first order Murnaghan equation of state. Differences between these compounds are discussed in terms of 5f electron delocalisation.Download full text in PD